Mat consisting of filament loop aggregations and method and apparatus for producing the same

ABSTRACT

In this mat consisting of filament loop aggregations, the filament loop aggregations wherein irregular form loops are formed in the upright direction by respectively winding to be coil-like many filaments coarse in the arranging intervals and made of a thermoplastic synthetic resin and are fused in the intersecting parts are overlapped above and below an intermediate filament loop aggregation layer high in the filament density and formed of coiled loops in the partly or all laterally fallen direction.

BACKGROUND OF THE INVENTION

This invention relates to a coarse net-like developed resilient mat madeby complicatedly entangling synthetic resin monofilaments and moreparticularly to a mat consisting of filament loop aggregations andadapted to a porch mat of fixed dimensions or a floor mat formed andlaid in a long sheet and a method and apparatus for producing the same.

Instead of a conventional carpet mat or synthetic resin mat, there isrecently provided a three-dimensional net-like mat consisting ofsynthetic resin monofilaments high in the water permeability and quickdryability. Due to such characteristics as the resiliency andweather-proofness, such three-dimensional net-like mat is used in manyindoor and outdoor fields, is applied particularly to such water usingplace as, for example, an inlet and outlet of a bath room or a pool sideand is appreciated because it is simple to wash and dry.

Also, as this kind of three-dimensional mat is open, the sand andgravels brought when it is trod will drop down and will not remain onthe surface. As water or the like also will drop down, the surface canbe always kept dry. It is thus convenient.

In addition, when such elastic sheet as a synthetic resin sheet, foamingsheet or rubber sheet is pasted to the lower surface of such mat, thecushioning property as of a mat will be able to be increased, the sandand water dropping from the surface will be able to be received by thissheet pasted to the lower surface and the floor will be able to beprevented from being made dirty directly by the dropping sand and thelike.

DESCRIPTION OF THE PRIOR ART

As disclosed in the gazette of a Japanese patent publication No.14347/1972, such three-dimensional net-like mat is formed as a non-wovenfabric wherein many monofilaments made of a thermoplastic syntheticresin are laminated while being rubbed and bend, are fused at theircontact points and are cooled to be solidified.

The formation of upright loops disclosed in the gazette of a Japanesepatent publication No. 31222/1980 and a Japanese patent laid open No.85061/1987 is known as a web forming means of the above mentionedfilaments in such non-woven fabric.

Now, in the non-woven fabric formation by the above describedconventional means, in such rubbed and bent web formation, theresiliency of the individual rubber and bent filament form part itselfis low, the rubbed and bent filaments by this producing means overlap oneach other to fall down and, as a result, as the entangled density ofthe filaments becomes higher, the resiliency of the sheet will be lost.

Thus, when the mat is used, the treading touch will be obstructed and,when the mat is stored or carried, it will be difficult to wind in thesheet-like mat, much to the inconvenience.

On the other hand, when the web formation is made loop-like, theresiliency of the filament itself in each loop-like part will bedeveloped but, in the web made of arcuate loops arranged in asubstantially fixed form, the respective loops are only fused at theirintersecting points and the contact points between the adjacent loops,are high in the independency and are therefore low in the resiliencyagainst treading and, as a result, no favorable treading touch will beobtained.

SUMMARY OF THE INVENTION

Therefore, the present invention has it as an object to provide a matwherein a filament web is formed of positively closed loops to develop afilament resiliency in each loop part and the degree of the contactfusing between the respective loops is made high to be able to develop astrong sheet resiliency and a method and apparatus for producing thesame.

DESCRIPTION OF THE DRAWINGS

The many advantages and features of the present invention can be bestunderstood and appreciated by reference to the accompanying drawingswherein:

FIG. 1 is a side view of an essential part showing an embodiment of theapparatus of the present invention; and

FIG. 2 is a side view showing an example of the mat of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

In order to attain such object, according to the present invention, amat consists of upright disarranged loop-like synthetic resin filamentthree-dimensional aggregations and has many spaces within it to developa cushioning property.

There is suggested a mat of a multilayer structure wherein areoverlapped aggregations each having coiled loops formed in the uprightdirection on both front and back sides by intermediately holding a highfilament density aggregation layer of coiled loops overlapped in thelaterally fallen direction.

In order to form such mat, several hot filaments of a thermoplasticsynthetic resin are pressed and extruded through T-die orifices and aremade to fall toward a water surface.

A pair of guide rollers are set as opposed to each other below a watersurface and a bundle of the above mentioned filaments is lowered so asto drop between these rollers.

The falling hot filaments are heated by such heat sources as ceramic farinfrared ray heaters so as not to be cooled by the atmosphere.

Such hot filaments are easy to make coiled loops on the water surface.Unless the filaments are hot, the loops will become large. Further, inthe filaments of a reduced temperature, no coiled loop will be formedbut only a channeled rubbed and bent form will be able to be made.

The height from the die mouth end to the water surface is 5 to 100 cm.and the heat reduction of the filaments is prevented by making the diemouth end approach the water surface as much as possible.

The orifice diameter of the T-die is 0.3 to 1.5 mm. as an elementdetermining the filament diameter, retains the resiliency and durabilityof the formed filaments and prevents the permanent set.

A mat sheet consisting of filament aggregations of respective widths canbe made by arranging the numbers of orifices corresponding to the widthsof 90, 120 and 150 cm. of intended mat sheets with an orificearrangement of a T-die of 3 to 6 longitudinal rows at the intervals of 3to 5 mm. and a pitch of 3 to 5 mm. in the lateral row.

That is to say, a hot filament bundle extruded out of the T-die of suchorifice arrangement is made to fall upright toward cooling water and isreceived by submerged rolls of a rotary peripheral speed well slowerthan the falling speed to limit the falling speed in water and to givethe filaments a resistance toward the water surface from the abovementioned rolls. Loops having a peripheral length of a filament lengthcorresponding to the difference between the extruding speed of therespective filaments and the falling speed in water will be sequentiallycontinuously formed to be coil-like on the water surface by thisresistance.

At this time, in order to make it easy to form loops and to make bentirregular loops, it is effective to keep boiling the cooling watersurface between the inclined panels.

This boiling state vibrates the respective filaments wound on the watersurface. As a result, entangled disarranged coiled loops are induced onthe water surface.

In order to make the boiling state on the water surface between theinclined guide panels, it is important to keep the filaments coming outof the T-die at a high temperature until the liquid level. Generally,when the filaments are in contact with the atmosphere, the filamenttemperature will quickly reduce. The water surface heated by the fallingin water of the filament bundle kept at a filament extruding moldingtemperature of 200° to 150° C. by the above mentioned heating treatmentto prevent air cooling in the filaments coming out of the T-die will bein the boiling state. Therefore, when the cooling water is kept at ahigh temperature of 60° to 80° C., this boiling will be made positive.

When the filaments are molded to be coiled loops while kept at a hightemperature, the fusing between the loops will be accelerated. Further,when the cooling water is at a high temperature, in case the moldedloops are pulled out into the atmosphere by the guide rolls and are sentto the secondary process, they will be able to be easily dried with coolor hot air.

A filament loop aggregation in which the coil density is made coarse byincreasing the rotation (pulling speed in water) of the rolls in waterand is made high by reducing the pulling speed is formed.

On the other hand, even if the thickness width of the hanging filamentbundle is not regulated, a three-dimensional formation of a coiled loopwill be able to be made. However, the size of the loop formed on theliquid surface is not fixed. Therefore, a means of regulating thethickness width of the filament bundle functions effectively to makeuniform coiled loop aggregations of an intended thickness.

As the pair of guide rollers are just below the water surface andregulate the positions of the filaments having sunk while describingloops, the thickness width of the filament bundle in the water surfaceposition just above them will be regulated as related with theregulation below the water surface.

Such filament loop aggregations are made in two parallel places and theother aggregation is formed along one side surface of one aggregation.

In such formation, when the above mentioned one aggregation is heated onthe side surface to be about the fusing temperature, the filaments ofthe side surface will soften and will form an aggregation layer high inthe filament density by the lateral fall of loops.

In molding synthetic resins, the general temperature as of the coolingbath is about 50° C. for PE (polyethylene) and PP (polypropylene), about10° to 40° C. for PVC (polyvinyl chloride) and about 85° C. for PS(polystyrene).

The surface tension of water on PVC (polyvinyl chloride) is so high asto be about 60 to 70 dym./cm. that fine filaments of an outside diameterless than 1 mm. will be overlapped in turn above the water surface, thecoiled loops formed here will be laminated in several steps and will becooled in water and therefore the object aggregations coarse in the loopclearances will not be obtained. Therefore, in order to sequentiallysink the coiled loops on the surface, it is effective to add a surfaceactive agent reducing the surface tension of the cooling bath.

EMBODIMENTS

FIG. 1 is a side view showing component parts in an optimum apparatusfor embodying the present invention. Respectively two filaments 2a and2b are to lower vertically toward cooling water 5 while being molded inthe thickness direction (longitudinal direction) in separate positionsfrom a T-die 1 extruding a thermoplastic synthetic resin material underpressure.

In the lateral direction (front to back direction on the paper surface)of the T-die in this case, many filaments 2a and 2b are to be molded asarranged at predetermined intervals (pitch of 3 to 5 mm.) in a lengthrange corresponding to the lateral width of an intended molding.

In the falling zone of these filaments 2a and 2b, bar-like ceramic farinfrared ray heaters 3a and 3b are arranged on both sides of therespective filament bundles so as to be heating heat sources.

In the filament 2a falling zone, just below the water surface, a pair ofguide rollers 4a and 4b are arranged at a predetermined spacing so thatthe bundle of the above mentioned filaments 2a may fall on the watersurface in this clearance and may be led by these rollers 4a and 4b tosink.

Also, a feeding roller 6 rotated and driven at a constant speed isarranged in water so that the bundle of the filaments 2a having sunk inthe above mentioned water may be moved in the cooling water 5 as heldbetween it and the above mentioned guide roller 4b. As many engagingpins 8 are erected at intervals on the peripheral surface of this roller6 in water and the rotary peripheral speed of the roller 6 rotating at aconstant speed is set at a speed lower than the falling speed of thefilaments 2a, the filaments 2a falling from the T-die 1 at a high speedwill be decelerated in sinking in water by the above mentioned roller 6in the water and will be, as a result, relaxed by the filament lengthcorresponding to the difference between these falling speed and sinkingspeed. These relaxations will concentrate in the water surface zone dueto the buoyancy of the filaments 2 of a small specific gravity. As aresult, the filaments 2a will form loops on the water surface.

That is to say, the filaments 2a extruded out of the T-die will reachthe water surface of the cooling water 5 while being kept near thetemperature at the time of molding by heating by the above mentionedheaters 3a in the falling zone in air. The filaments 2a having sunk inthe cooling water 5 will quickly lower in the temperature and will behardened. However, these hardened filaments 2a will be regulated in thepulling amounts by the submerged rollers 6 stopped in sliding by theengaging pins 8, therefore the hardened parts in water will be subjectedto resistances from the submerged roller 6 and thereby the softfilaments 2a still at a high temperature just before reaching the watersurface will be curved and will be gradually pulled into water whiledescribing loops to form coil-like loops.

When the temperature within the bath of this cooling water 5 is kept at60° to 80° C., the cooling water 5 in the falling position will belocally boiled by heating by the filaments 2a reaching the water surfacewhile at a high temperature. By this boiling, the water surface of thatpart will be waved and greatly rocked and therefore the filaments 2describing loops on this water surface will be waved and disarranged inresponse to the rocking of the water surface.

Therefore, the disturbed form loops will be prevented by theconcavo-convexes by the disarrangement from the total surface contactbetween the adjacent loops overlapped on the water surface and will havecomparatively many contact point parts.

In such contact part, the loops will be fused with each other betweenthem and will be cooled to be hardened. Therefore, coiled loops havingcomparatively many fused parts between the adjacent loops will becontinuously formed in turn and a filament loop aggregation A in whichcoiled loops are cross-linked longitudinally and laterally with the loopedges overlapping between the adjacent filaments 2 will be formed.

With the above formation as a first filament loop aggregation formingstep, the aggregation A moving in the above mentioned cooling water 5will be engaged with a guide roller 7b of a pair of guide rollers 7a and7b arranged just below the water surface in the falling zone of theother filament 2b and will be pulled up so as to be exposed at least onone surface above the water surface.

A ceramic far infrared ray heater 9a is arranged in the exposed positionof this aggregation A so that the aggregation A may be dried and heatedon the surface to be near the fusing temperature while moving.Therefore, the loops near this heated surface will soften in thefilaments and will overlap as laterally fallen to form a filament looplayer C high in the filament density and will be further softened andfused on the surface. This aggregation A will detour the guide roller 7band will be again pulled into the cooling water 5. Filaments 2b hangdown between the above mentioned heated surface and the other guideroller 7a in this pulling zone.

Further, another submerged roller 10 is arranged in the water sinkingzone of the filaments 2b. The filament bundle is moved at a low speedwhile engaged with the engaging pins 8 on the peripheral surface of theroller 10. As the moving speed of the filament bundle in water is madelower than the falling speed of the filaments 2b falling down from theT-die, the same as in the above described first filament loopaggregation forming step, an aggregation B in which irregular loops onthe water surface are formed to be coil-like will be obtained. 9brepresents a heating ceramic far infrared ray heater present in thefalling zone of the filaments 2b. 11 represents a reflecting plate.

When this aggregation B molding step is made a second filament loopaggregation molding step, in this second step, the aggregation B will befused and connected on one side with the heated surface of the abovementioned aggregation A.

Therefore, the product formed under cooling in water through the abovementioned step is a mat of an overlapped structure of the aggregations Aand B consisting of vertically upright loops holding in the centerbetween them an aggregation layer C of laterally fallen direction loopsas shown in FIG. 2.

By the way, the means of forming the above mentioned aggregation layer Cis not limited to be as in the above illustrated embodiment. Forexample, a separately formed aggregation layer C consisting of laterallyfallen loops may be bonded to the aggregation A or B formed of loops inthe upright direction. Each of the guide rollers 4a, 4b and 9a, 9b maybe arranged so as to be exposed on a part of the peripheral surfaceabove the water surface.

By the way, in order to pull the coiled loops formed on the coolingwater surface into water without disturbing their form, a surface activeagent is added into cooling water 4.

    ______________________________________                                        Amounts of addition of the surface active                                     agents per 100 parts of water:                                                ______________________________________                                        Anionic system:                                                               Alkylbenzenesulfonate:  1 to 0.2 part                                         Dialkylsulfosuccinate:  1 to 0.05 part                                        Noninonic system:                                                             Polyoxyethylene nonylphenol ether:                                                                    1 to 0.1 part                                     

It is effective to add 0.05 to 0.2% dialkylsulfosuccinate which is highin the capacity of reducing the surface tension and in the connectingeffect with a slight amount.

Now, in this kind of apparatus, in order to keep the cooling bath levelconstant, cooling water is circulated with a pump while beingoverflowed. In such case, many bubbles will be generated in an auxiliarytank level detecting electrode and cooling bath and will bedisadvantageous in molding. In this respect, at the above mentionedeffective component concentration of the dialkylsulfosuccinate, manybubbles tend to be generated. Therefore, it can be said to be optimum toadd and use preferably 0.05 to 0.2% dialkylsulfosuccinate.

The mat material consisting of the thus formed filament loopaggregations A and B may be coated with a plastisol made of the samematerial mixture as of the filament to prevent the bonding strengthreduction and permanent set of the filament loops.

A back sheet B consisting of a resin sheet, foamed sheet or rubber sheetmay be used as bonded to the back surface of the mat material inresponse to the object of use of the product.

(Formation Example 1)

    ______________________________________                                        Polyvinyl chloride (PVC) (P-1300)                                                                   100      parts                                          Plasticizer DOP Dioctyl phthalate                                                                   50       parts                                          Stabilizer Dibutyl tin laurate                                                                      2        parts                                          Stabilizer Cadmium stearate                                                                         0.6      part                                           Stabilizer Barium stearate                                                                          0.4      parts                                          Coloring agent        0.1      parts                                          ______________________________________                                    

A compound material of the above mentioned mixture is molded to befilaments by an extruding molder.

The distance between the guide rollers 4a and 4b below the cooling watersurface is set to be 8 mm. The distance between the guide roller 4b andsubmerged roller 6 is 9 mm. The distance between the other guide rollers7a and 7b is 16 mm. The filament molding orifice diameter is 0.8 mm. TheT-die orifice arrangement is of two longitudinal rows at the intervalsof 5 mm. and a lateral orifice pitch of 5 mm.

The distance between the T-die and cooling water surface is 5 cm. Thedie temperature is 185° C. The cooling water temperature is 60° to 80°C. Four ceramic far infrared ray heaters of 1.5 KW each are used. At amolding linear speed of 2 m. per minute, loops at a speed of 40 cm. perminute can be made.

In this formation, by only holding the filament bundle in its thicknesswidth direction with the guide rollers, the front and back surfaces ofthe aggregations can be uniformed and the mat shown in FIG. 2 isobtained and is made a product through drying and bonding steps.

As the extruder die pressure is applied and hot filaments are extrudedinto air, the finished dimension of the filament is 0.2 mm. thicker thanthe filament orifice of a diameter of 0.8 mm. of the T-die and afilament coil structure of a diameter of 1 mm. is made. Even if thedistance between the guide rollers 7a and 7b is set to be 16 mm., theaggregation molded under the width regulation by this distance willshrink when the filament is hardened and will be therefore 13.5 to 14mm. thick.

(Effects of the Invention)

Thus, according to the mat of the present invention, as an aggregationis formed of irregular form loops by winding filaments to be coil-like,the individual closed loops well develop the filament resiliency, are ofsuch irregular form as a wavy form and are therefore high in the degreeof contact fusing between the adjacent continuous coiled loops andbetween the filament forming loops arranged longitudinally and laterallyand thus a mat high in the bonded degree as a whole can be obtained. Inthe aggregation part in which such loops are formed in the uprightdirection, in addition to the resiliency of the above mentioned loopsthemselves, a stiff mat resiliency can be obtained by the strength ofthe bonded degree between these loops. The aggregation layer high in thefilament density is high in the strength, particularly, in the tensilestrength, is so high in the clogged degree as to allow sand or water todrop from the upper part of the mat and, on the other hand, to preventit from springing up from the lower surface. Therefore, the mat of thepresent invention of doubly overlapped filament loop aggregations withsuch aggregation layer held between them is so high in the resiliencyand tensile strength as to be optimum to be used for a porch mat orfloor sheet very high in the treading touch.

When the diameter of the filament in this case is set to be in the rangementioned in claim 2, the practical strength of the filament loop can beobtained and, on the other hand, the mat can be made high in the sheetweight convenient to the setting work and in the treading touch.

When the major diameter of the loop of an irregular form is adjusted tobe in the range mentioned in claim 3, it will be effective in keepingthe mat elasticity but, on the other hand, if the major diameter of theloop is too large, a shoe tip or like will catch on and cut the loop andsuch danger as falling down will be likely to be caused. Thus, it is notpreferable.

In the method of forming a mat or sheet consisting of such filament loopaggregations, the filaments are lowered onto the water surface whilenear the molding temperature and, when this water surface is waved byboiling, the loops formed on the water surface will be able to be insuch irregular forms as wavy forms and to be contact-fused in the loopintersecting parts and between the loops.

In addition, there are auxiliary effects that, when the filament bundlefalling toward the cooling water surface is regulated in the directionof contracting from outside the width of the thickness direction of thebundle, the sizes of the respective loops formed of these filaments willbe able to be uniformed and, when the contracted width is controlled,the formation of combining the above described upright direction loopsand laterally fallen loops will be able to be freely made.

If the distance from the T-die to the cooling water surface is long, thefilament temperature will be reduced by air cooling between them.Therefore, it is desirable to set the distance to be as short aspossible. However, if they are too adjacent, the loop formation on thewater surface will be disturbed. Therefore, this distance of 5 to 10 cm.is effective.

By keeping the temperature of the cooling water at a comparatively hightemperature of 60° to 80° C., a local boiling state in which the watersurface on which the filaments fall is properly waved by heating by thefilaments submerging into water can be automatically obtained. In orderto smoothly sink the filaments to prevent the loop forms from beingdisturbed, it is effective to add a surface active agent.

What is claimed is:
 1. A mat consisting of filament loop aggregations wherein the filament loop aggregations in which irregular form loops are formed in the upright direction by respectively winding to be coil-like many filaments coarse in the arranging intervals and made of a thermoplastic synthetic resin and are fused in the intersecting parts are overlapped above and below an intermediate filament loop aggregation layer high in the filament density and formed of coiled loops in the partly or all laterally fallen direction.
 2. A mat consisting of filament loop aggregations according to claim 1 wherein the diameter of said filament is in the range of 0.3 to 1.5 mm.
 3. A mat consisting of filament loop aggregations according to claim 1 wherein the major diameter of said loop is in the range of 3 to 15 mm.
 4. A method of producing a mat consisting of filament loop aggregations characterized in that, between the first filament loop aggregation forming step wherein many filaments arranged at intervals longitudinally and laterally are continuously molded by extruding a thermoplastic synthetic resin out of a T-die, are present on a cooling water surface boiling as kept by heating at a filament temperature close to the temperature at the time of molding while this filament bundle is vertically lowered toward the cooling water surface and are sunk in the vertical direction as controlled to be at a speed lower than the extruding molding speed of these filaments and the second filament loop aggregation forming step progressing simultaneously with the first step, the aggregation processed in said first step is once pulled up on the water surface, is fed into the filament bundle falling water surface zone in said second step while being heated on one side surface near to the fusing temperature and is formed by making said heated surface a loop forming surface on one side of the filament bundle in said second step.
 5. A method of producing a mat consisting of filament loop aggregations according to claim 4 wherein the distance from the lower surface of the T-die to the water surface is in the range of 5 to 10 cm.
 6. A method of producing a mat consisting of filament loop aggregations according to claim 4 wherein cooling water held at a temperature of 60° to 80° C. is locally boiled by heating by sinking loops just below the fall of said filaments.
 7. A method of producing a mat consisting of filament loop aggregations according to claim 4 wherein about 0.05 to 0.2% surface active agent dialkylsulfosuccinate is added into cooling water.
 8. A method of producing a mat consisting of filament loop aggregations according to claim 4 wherein about 0.05 to 0.2% surface active agent dialkylsulfosuccinate is added into cooling water. 